First, the supplements used to treat depression aren't necessary for health unless you had a deficiency severe enough to cause it -- for example, a lack of B vitamins could result in depression. Your blood tests didn't show these deficiencies or your doctor would have advised you to take more. The natural program for dealing with depression involves taking a collection of substances, not just one, and would also include therapy, exercise, meditation, and the like -- a holistic treatment, not just taking one thing. Most of the things used are herbs, for which there is no nutritional need, and amino acids which you're unlikely to be deficient in unless you eat no protein. Start your homework with a book called Natural Highs by Hyla Case, a psychiatrist affiliated with UCLA, which gives an overview of how natural medicine is used for mental disorders. Then, because you don't really know anything about this, look for a naturopath or doctor who practices integrated medicine for help putting together a program that will probably involve experimentation. Also know that the vast majority of doctors not only know nothing at all about supplements, they don't believe in them. After all, natural medicine competes with their income. Make sure your doctor, though, has tested you for all the physiological problems that can cause mental disorders, such as thyroid problems, blood sugar imbalances, hidden viruses and bacterial infections, etc. These require special blood tests your doctor might not have done.
what type of blood tests did you have done?